Catalysts have been used widely in the refining and chemical processing industries for many years. Hydroprocessing catalysts, including hydrotreating and hydrocracking catalysts, are now widely employed in facilities worldwide. Used or “spent” hydroprocessing catalysts discharged from these facilities typically contain metal components such as molybdenum, nickel, cobalt, vanadium, and the like.
With the advent of heavier crude feedstock, refiners are forced to use more catalysts than before for hydroprocessing and to remove catalyst contaminants and sulfur from the feedstock. These catalytic processes generate huge quantities of spent catalyst. With the increasing demand and market price for metal values and environmental awareness thereof, catalysts can serve as a secondary source for metal recovery.
In order to recycle catalytic metals and provide a renewable source for the metals, efforts have been made to extract metals from spent catalysts, whether in supported or bulk catalyst form. US Patent Publication No. 2007/0025899 discloses a process to recover metals such as molybdenum, nickel, and vanadium from a spent catalyst with a plurality of steps and equipment to recover the molybdenum and nickel metal complexes. U.S. Pat. No. 6,180,072 discloses another complex process requiring solvent extraction as well as oxidation steps to recover metals from spent catalysts containing at least a metal sulphide.
There is still a need for an improved and simplified process to recover metals including but not limited to molybdenum, nickel, and vanadium from spent catalysts.